1. Field of the Invention
The invention relates to a friction clutch having a progressive engagement action, and concerns more particularly such clutch in which the means of axial shock reduction which ensure this progressivity are incorporated into the pressure plate.
In a friction clutch, axial shock reduction means are provided to ensure a clutch engagement without unnecessary jolting and thereby to improve driving comfort. For certain powerful vehicles, progressivity in the clutch is a necessity. Until now, the means of axial shock reduction ensuring this progressivity of engagement have often been combined with the friction disc.
2. Description of the related art
Attempts have been made to decrease the inertia of the friction disc and consequently to simplify its structure. With this in mind, friction discs without means of axial shock reduction have been devised, these latter then being combined with other elements of the clutch assembly.
Such an arrangement is shown in U.S. Pat. No. 4,619,353 which describes a system in which the pressure plate is in two parts spaced apart axially and movable with respect to one another. It consists in fact of two plates joined to one another by small tangential tongues, one of the plates being applied against the friction disc at the moment of clutch engagement whilst the other is entrained by the means of operation. The two plate unit is joined to the cover by other small tangential tongues. Consequently, each plate is of necessity provided with radial tabs, for fixing the tongues, spaced circumferentially, which necessitates the provision of larger circumferential detachments in the periphery of the cover, weakening the latter. Moreover, the axial length of the pressure plate is increased, everything else being equal, which can constitute a serious disadvantage for the installation of the clutch in a vehicle, with a transverse engine for example.